There are two major types of commercial polymeric roofing membranes, namely those made from crosslinked ethylene/propylene/diene monomer (XL-EPDM) interpolymers and those made from thermoplastic polyolefin (TPO). TPO-based materials offer improved recyclability and sealability over commercial XL-EPDM materials. TPO-based materials, however, generally offer poor low temperature flexibility.
Thermoplastic Vulcanizate (TPV) materials, including XL-EPDM dispersed in a TPO polymeric matrix wherein the XL-EPDM has a particle size of several microns, have been developed for use in roofing membranes. In such materials, the TPO matrix may, in some instances, be a polypropylene (PP) in which the XL-EPDM interpolymer is miscible. Theoretically, TPV materials provide both the recyclability and sealability of TPO-based materials and the good low temperature flexibility of XL-EPDM materials.
Although numerous types of thermoplastic vulcanizates are known, there is still a need for further improvements on thermoplastic materials having good elastomeric properties. Specifically, there is a need for a method to produce thermoplastic vulcanizate with improved tensile strength, elongation, tear strength and processability.